METABOLISM IN FEVER AND CERTAIN INFECTIONS 101 



or four hours are used. The amount of heat stored in the body cannot be 

 determined exactly by means of the rectal temperature in short periods 

 since no one spot in the body gives an accurate index of the temperature 

 change of the whole body. In few diseases has the agreement between 

 the direct and indirect methods been closer than the above, and although 

 it is impossible by this method to rule out minor changes in the metabolism 

 we can say that there is no reason to suspect any profound change in the 

 oxidative processes or any interference with the law of the conservation of 

 energy. 



The Regulation of the Body Temperature. Attempts have been made 

 to determine the mechanism of temperature regulation by means of indi- 

 rect calorimetry. If we know the amount of heat produced in the body 

 and assume that the changes in the rectal temperature indicate the changes 

 in the average temperature of the whole body we can calculate the heat 

 elimination during the experimental period. Each kilogram of body is 

 equivalent to about 0.83 liter of water in its power to store heat. A 

 man weighing 70 kg. has the hydrothermal equivalent of about 58.1, and 

 if the temperature rises one degree C. it means that 58.1 calories have 

 been stored in the body, if it falls one degree the same amount has been 

 lost. In the long ran this method gives fairly good results, but as we shall 

 see later it is not always satisfactory to assume that a single thermometer 

 placed in the mouth or rectum indicates with sufficient rapidity the 

 changes in the extremities or in the large proportion of the whole mass 

 which lies just beneath the skin. Barr and Du Bois have calculated 

 that in a man who weighs 70 kg. about 15 kg. is within 1 cm. of the 

 surface. 



The respiration calorimeter which measures both heat production by 

 chemical methods and heat elimination by physical methods furnishes an 

 exact means of determining how the body temperature is raised or lowered 

 in fever. Isaac Ott(a), of Philadelphia, in 1892, and Likatscheff and 

 Avroroff, of Petrograd, in 1902, measured the heat elimination of malaria 

 patients in calorimeters but did not use for their calculations the method 

 of indirect calorimetry. Coleman and Du Bois, using both methods, 

 published diagrams showing the relationship of heat production and elim- 

 ination in all the experiments where the methods of direct and indirect 

 calorimetry agreed within 5 per cent. In these experiments the small 

 difference between the two meant that the rectal temperature curve was 

 close to that of the average body temperature. After several years' work 

 with many diseases had shown the accuracy of the Sage calorimeter Barr 

 originated another method of calculation which permits us to obtain much 

 valuable information from the typhoid experiments previously discarded, 

 namely those in which the direct and indirect methods differed by more 

 than 5 per cent. 



